High efficiency lighting system

ABSTRACT

A high efficiency lighting system maintains normal lighting conditions by lighting fixtures requiring DC electrical power. A power control device receives AC electrical power from a public utility converts AC power to DC power and delivers low voltage DC electrical power to lighting fixtures. A standby battery is provided to maintain power during power outages. Optionally, a photovoltaic DC electrical power source may be connected to the power control device, to provide alternate DC electrical power. In a further embodiment, a gas driven cogenerator unit may supply DC electrical power.

[0001] This application is a continuation-in-part of application Ser.No. 08/606,219 filed Mar. 7, 1996, which is a continuation-in-part ofapplication Ser. No. 08/328,574, filed Oct. 24, 1994, now U.S. Pat. No.5,500,561 dated Mar. 19, 1996, which was a continuation of applicationSer. No. 08/129,375, filed Sep. 29, 1993, which is a continuation ofapplication Ser. No. 07/944,796, filed Sep. 14, 1992, which is acontinuation of application Ser. No. 07/638,637, filed Jan. 18, 1991.

BACKGROUND OF THE INVENTION

[0002] The field of the invention is high efficiency uninterruptablelighting systems.

[0003] Uninterruptable power supplies are well known accessoriesespecially when applied to computer equipment to “ride out” brief poweroutages so that no data is lost or compromised. Some have more batterystorage capability so that operation may be maintained for an extendedoutage. Some special lighting systems are also protected in a similarfashion by an uninterruptable power source for critical applicationssuch as operating rooms in hospitals. In lieu of such systems, reducedamounts of auxiliary emergency lighting is provided for special areas bymodular systems which are only engaged during power outages; thesemodules are often used in stairwells and consist of a housing enclosinga battery, charger, power sensor and one or two flood lamps.

[0004] These prior art systems do nothing to enhance lightingefficiency, and would not be considered as substitutes for conventionallighting.

OBJECTS OF THE INVENTION

[0005] It is an object of this invention to provide an uninterruptablelighting system that can be routinely substituted for conventionalbuilding or office lighting.

[0006] It is another object of this invention to provide high efficiencyoperation with lower operating cost than conventional incandescent andfluorescent lighting systems.

[0007] It is yet another object of this invention to provide long termuninterruptability (3 hours +) with small storage volumes.

[0008] It is an object of this invention to provide optimum batterymanagement for long storage life, ultra low maintenance, and economicaloperation.

[0009] It is a further object of this invention to provide foreconomical connection to an alternate energy source such as a solarphotovoltaic (PV) panel.

[0010] It is another object of this invention to provide a system withenhanced safety through low voltage operation between the power controlunit and the lighting fixtures.

[0011] It is yet another object to achieve high power quality with lowinterference through very high power factor and low total harmonicdistortion.

[0012] It is an object of this invention to provide for expansion of thelighting system through a modular approach to increase subsystem andcomponent standardization to reduce cost.

SUMMARY OF THE INVENTION

[0013] In keeping with these objects and others which may becomeapparent, the present invention includes a high efficiency lightingsystem for maintaining normal lighting conditions by lighting fixturesrequiring DC electrical power.

[0014] The system includes a power control means for receiving ACelectrical power from a grid source and delivering required low voltageDC electrical power to the lighting fixtures. The power control meansconverts the AC electrical power to DC electrical power.

[0015] A battery provides, on a standby basis, the required DC lowvoltage electrical power to the power control means. The battery isconnected to the power control means so that the battery may bemaintained in a fully charged condition by the power control meansduring normal supply of AC electrical power from the grid source.

[0016] The power control means delivers required DC electrical powerfrom the battery to the lighting fixtures during an AC electrical poweroutage to maintain the power without interruption.

[0017] The power control means can be a plurality of multiple powercontrol means, each connected to its own battery for maintaining thelighting in a building with multiple rooms.

[0018] An optional photovoltaic source of DC electrical power may beconnected to the power control means for reducing the amount ofelectrical power taken from said grid source.

[0019] The battery provides, on a standby basis, DC low voltageelectrical power to the power control means, which power control meansmaintains the battery in a fully charged condition by electrical powerfrom an AC grid source.

[0020] In a version using AC power input only without an auxiliarybattery or photovoltaic panel, the high efficiency lighting system formaintaining normal lighting conditions of lighting fixtures requiring DCelectrical power, includes the power control means for receiving ACelectrical power from a grid source and delivering required DCelectrical power to the lighting fixtures, as well as a power controlmeans converting AC electrical power to DC electrical power.

[0021] In a further embodiment for remote use, such as a remote campsitewithout access to conventional AC power, a high efficiency lightingsystem maintains normal lighting conditions of lighting fixturesrequiring DC electrical power. The remote system includes a powercontrol means for receiving DC electrical power from a photovoltaicpanel and delivering required low voltage DC electrical power to theremote lighting fixtures, and the power control means controls chargingof a battery.

[0022] The battery also provides, on a standby basis, the required DClow voltage electrical power to the power control means. It is connectedto the power control means while being maintained in a charged conditionby the power control means, during daylight hours of input of power fromthe photovoltaic panel.

[0023] Moreover, the power control means delivers required DC electricalpower from the battery to the lighting fixtures during periods of timewhen power from the photovoltaic panel is not available, such as atnight times.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention can best be understood in conjunction withthe accompanying drawings, in which:

[0025]FIG. 1 is a block diagram of basic uninterruptable lightingsystem;

[0026]FIG. 2 is a physical block diagram of basic uninterruptablelighting system;

[0027]FIG. 3 is a wiring layout of a single lighting module;

[0028]FIG. 4 is a wiring layout of a four module system;

[0029]FIG. 5 is a block diagram of lighting system with a PV panel;

[0030]FIG. 6 is a front view of power control unit;

[0031]FIG. 7 is a wiring diagram and specs for two lamp ballast;

[0032]FIG. 8 is a wiring diagram and specs for single lamp ballast;

[0033]FIG. 9 is a front view of battery enclosure; and

[0034]FIG. 10 is a block diagram of power control unit.

[0035]FIG. 11 is a block diagram of an alternate lighting system usingnatural gas cogeneration.

DETAILED DESCRIPTION OF THE INVENTION

[0036]FIG. 1 shows a block diagram of the major components of anuninterruptable lighting system of this invention. It may be installedanywhere conventional building lighting is required. Unlike emergencylighting, this is a full service, high quality lighting product. Itfunctions with standard fixtures and lamps, without compromise in outputquality and with no flicker in the event of a power failure. Thispermits normal building activities to continue for several hours usingbattery storage without disruption of work activity due to loss oflighting. The key subsystem that ties the entire system together is thepower control unit 1 which normally uses AC grid power to supply thelighting energy and keep the battery 2 charged. The lighting fixtures 3are fluorescent tubes using electronic ballasts which have a low voltage(nominal 26.6 volts) DC input supplied by line 5 from power control unit(PCU) 1. During a power outage, the DC line 5 is supplied by battery 2.

[0037]FIG. 2 shows a physical block diagram showing the AC electricservice panel 6 with a three wire cable system supplying either 120 or220 VAC to PCU 1. Battery case 7 contains two group 24/27 deep dischargelead acid storage batteries wired in series and through a 30 amp fuse tothe PCU 1. The wiring to all lighting fixtures 3 is at a nominal 26.6volts DC. In the preferred embodiment, each PCU can power ten two tube48 inch T8 fluorescent fixtures or 20 single tube fixtures.

[0038]FIG. 3 shows a wiring layout for three offices as controlled by asingle PCU 1. A closet area 17 is used to house battery 2. The AC line 4leads to PCU I which is placed in the ceiling cavity. The DC wiring 5 tothe lighting fixtures is also in the ceiling cavity.

[0039] The 220 VAC input power to the PCU is 725 watts for an AC rms ofapproximately 3 amps. The equivalent 120 VAC unit will be about 6 amps.Because the PCU is power factor corrected to 0.99, a 20 amp circuitbreaker and number 12 wire can support a maximum of 3 PCU's from a 120volt line and 6 units from a 220 volt line for a total DC power outputof about 2100 watts and 4200 watts respectively.

[0040]FIG. 4 shows a wiring layout serving 8 small offices and fourlarger ones. This involves the use of four separate uninterruptablelighting systems using four PCU's 1 and four battery modules 2 locatedin four central closets 17. The four PCU's are supplied from a single220 VAC circuit breaker in power panel 6 via AC cable 4 as distributedfrom distribution box 20. Each of the lighting systems supplies 10 twolamp fixtures 3.

[0041]FIG. 5 shows an uninterruptable lighting system including a PVpanel 25.

[0042] As shown in FIG. 6, a front view of PCU 1, it is simply wired totwo terminals. This simple system configuration permits high securitylighting using an AC line, battery back-up, and PV shared contribution.A system with the PCU alone attached to the AC line is a viable lightingsystem that can pay for itself by providing high efficiency DC lighting.By adding the battery subsystem, the user achieves uninterruptablelighting. By using a system without a battery but with AC input and a PVpanel, the power savings of the PV contribution is achieved with thebalance supplied by the AC input. In an area remote from the AC grid, asystem using a PCU attached to a large PV panel and a larger battery cansupply totally solar lighting. The PCU is sufficiently flexible tosupport all of these configurations of lighting systems. It can alsosupply other DC loads besides lighting, such as for example, householdappliances, microwave ovens, heaters and the like. Furthermore, it canalso alternately accept external DC power from many varied sources suchas wind generators or engine powered generators.

[0043]FIG. 6 shows a front view of PCU 1 with finned heat sink 28 andterminal strip 29.

[0044]FIGS. 7 and 8 show the wiring diagrams and specifications for thetwo lamp and one lamp DC ballasts respectively (designated as NB2756/2and NB2727M respectively).

[0045]FIG. 9 shows a front view of the battery case with hinged lid 36and latches 37. It is a thermoplastic case rated only for sealed typelead acid batteries.

[0046]FIG. 10 shows a block diagram of the PCU. The AC input isrectified by DC Rectifier Means such as a bridge circuit. The PowerFactor Correction Means is used to achieve a high power factor (0.99) atthe AC input. The Control Means and Voltage Regulator means interactthrough circuits such as pulse width modulation and DC to DC switchingpower supply topologies to provide the nominal 26.6 volts to thelighting ballasts or other suitable DC loads through the power junctionmeans. Other voltages are also possible, such as 13.3, 26.6, 39.9 etc.

[0047] The Battery Undervoltage Cut-Off disconnects the battery insituations of depletion to prevent “over sulfation” or chemical andphysical damage to the storage battery. The PV Voltage Regulator andSuppressor is a power conditioner block to suppress voltage transients(such as from lightning strikes in the vicinity) and also to preventover charging of the storage battery from the PV panel.

[0048]FIG. 11 is an alternate embodiment for a loadside powered lightingsystem including natural gas in a cogeneration component. AC power 50 isnormally converted to DC power by DC power converter 51 and controlmeans 52. However, a cogenerator in the form of a DC gas generator 53receives natural gas from a natural gas source 54, and sends DC power tobuilding lighting system 55, such as electronic ballasted fluorescentlighting. This system provides a flatter and more predictable powerdemand for electric utility customers at building lighting system 55,since it supplants peak power from electric utility generating sources.This results in reduced demand charges, since gas offers a lower costper unit of energy consumed, compared to conventional AC power from apublic utility.

[0049] The cogeneration system can run continuously for lighting load55, without having to be sent back to AC line power 50, which avoids theneed for costly AC synchronization methods and sine wave purity, as isneeded when sending excess electricity back to a public utility.

[0050] DC gas generator 53 directly couples to building lighting system55 through a diode isolator that allows either AC or DC power to operatebuilding lighting system 55.

[0051] Other modifications may be made to the present invention withoutdeparting from the scope of the invention, as noted in the appendedclaims:

I claim:
 1. A high efficiency lighting system for maintaining normallighting conditions by lighting fixtures requiring DC electrical powercomprising: power control means for receiving AC electrical power from agrid source and delivering required low voltage DC electrical power tosaid lighting fixtures; said power control means converting said ACelectrical power to DC electrical power; battery means for providing ona standby basis said required DC low voltage electrical power to saidpower control means; said battery means being connected to said powercontrol means for being maintained in a fully charged condition by saidpower control means during normal supply of AC electrical power fromsaid grid source; and said power control means delivering said requiredDC electrical power from said battery means to said lighting fixturesduring an AC electrical power outage to maintain without interruptionnormal lighting by said lighting fixtures.
 2. The high efficiencylighting system of claim 1 having multiple power control means eachconnected to its own battery means for maintaining the lighting in abuilding with multiple rooms.
 3. The high efficiency lighting system ofclaim 1 having a photovoltaic source of DC electrical power connected tosaid power control means for reducing the amount of electrical powertaken from said grid source.
 4. A high efficiency lighting system forlighting fixtures requiring DC low voltage electrical power comprising:power control means for receiving AC electrical power from a grid sourceand delivering required low voltage DC electrical power to said lightingfixtures; said power control means converting said AC electrical powerto DC electrical power; photovoltaic means for delivering DC low voltageelectrical power to said power control means; said power control meansreducing the electrical power taken from said grid source by the amountof electrical power supplied by said photovoltaic means.
 5. The highefficiency lighting system of claim 4 having battery means for providingon a standby basis said required DC low voltage electrical power to saidpower control means, said power control means maintaining said batterymeans in a fully charged condition by electrical power from said gridsource, for maintaining without interruption the normal lighting by saidlighting fixtures during a power outage.
 6. A high efficiency lightingsystem for maintaining normal lighting conditions by lighting fixturesrequiring DC electrical power comprising: power control means forreceiving AC electrical power from a grid source and delivering requiredlow voltage DC electrical power to said lighting fixtures; said powercontrol means converting said AC electrical power to DC electricalpower.
 7. The high efficiency lighting system as in claim 6, furthercomprising a DC power cogenerator directly coupled to said lightingfixtures through a diode isolator allowing either AC or DC power tooperate said lighting fixtures.
 8. A high efficiency lighting system formaintaining normal lighting conditions by lighting fixtures requiring DCelectrical power comprising: power control means for receiving DCelectrical power from a photovoltaic panel and delivering required lowvoltage DC electrical power to said lighting fixtures; said powercontrol means controlling charging of a battery means; said batterymeans providing on a standby basis said required DC low voltageelectrical power to said power control means; said battery means beingconnected to said power control means for being maintained in a chargedcondition by said power control means during hours of input from saidphotovoltaic panel, and said power control means delivering saidrequired DC electrical power from said battery means to said lightingfixtures during periods of time when power from said photovoltaic panelis not available.
 9. A DC power supply system for DC loads requiring DCelectrical power comprising: power control means for receiving ACelectrical power from a grid source and delivering required low voltageDC electrical power to said DC load; said power control means convertingsaid AC electrical power to DC electrical power; battery means forproviding on a standby basis said required DC low voltage electricalpower to said power control means; said battery means being connected tosaid power control means for being maintained in a fully chargedcondition by said power control means during normal supply of ACelectrical power from said grid source; and said power control meansdelivering said required DC electrical power from said battery means tosaid DC load during an AC electrical power outage to maintain withoutinterruption normal operation of the DC load.
 10. The DC power supplysystem of claim 9 having a photovoltaic source of DC electrical powerconnected to said power control means for reducing the amount ofelectrical power taken from said grid source.
 11. The DC power supplysystem of claim 9 having a cogeneration source of DC electrical powerconnected to said power control means for reducing the amount ofelectrical power taken from said grid source.
 12. A DC power supply forDC loads requiring DC electrical power comprising: power control meansfor receiving AC electrical power from a grid source and deliveringrequired low voltage DC electrical power to said DC load; said powercontrol means converting said AC electrical power to DC electricalpower.
 13. A DC power supply system for DC loads requiring DC electricalpower comprising: power control means for receiving DC electrical powerfrom a DC power source and delivering required low voltage DC electricalpower to said DC load; said power control means controlling charging ofa battery means; said battery means providing on a standby basis saidrequired DC low voltage electrical power to said power control means;said battery means being connected to said power control means for beingmaintained in a charged condition by said power control means duringhours of input from said DC power source, and said power control meansdelivering said required DC electrical power from said battery means tosaid DC load during periods of time when power from said DC power supplyis not available.
 14. The DC power supply system as in claim 13 whereinsaid DC power source is a cogeneration unit.
 15. The DC power supplysystem as in claim 13 wherein said DC power source is a photovoltaicpanel.
 16. The DC power supply system as in claim 9 wherein said DC loadis a household appliance.
 17. The DC power supply system as in claim 9wherein said DC load is a microwave oven.
 18. The DC power supply systemas in claim 9 wherein said DC load is a heater.
 19. The DC power supplysystem as in claim 13 wherein said DC load is a household appliance. 20.The DC power supply system as in claim 13 wherein said DC load is amicrowave oven.
 21. The DC power supply system as in claim 13 whereinsaid DC load is a heater.